Gao Guoping, Jiao Yan, Ma Fengxian, Jiao Yalong, Waclawik Eric, Du Aijun
School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology (QUT), Garden Point Campus, QLD 4001, Brisbane, Australia.
School of Chemical Engineering, University of Adelaide, Adelaide, SA 5005, Australia.
Phys Chem Chem Phys. 2015 Dec 14;17(46):31140-4. doi: 10.1039/c5cp05512a.
Interfacing carbon nanodots (C-dots) with graphitic carbon nitride (g-C3N4) produces a metal-free system that has recently demonstrated significant enhancement of photo-catalytic performance for water splitting into hydrogen [Science, 2015, 347, 970-974]. However, the underlying photo-catalytic mechanism is not fully established. Herein, we have carried out density functional theory (DFT) calculations to study the interactions between g-C3N4 and trigonal/hexagonal shaped C-dots. We find that hybrid C-dots/g-C3N4 can form a type-II van der Waals heterojunction, leading to significant reduction of band gap. The C-dot decorated g-C3N4 enhances the separation of photogenerated electron and hole pairs and the composite's visible light response. Interestingly, the band alignment of C-dots and g-C3N4 calculated by the hybrid functional method indicates that C-dots act as a spectral sensitizer in hybrid C-dots/g-C3N4 for water splitting. Our results offer new theoretical insights into this metal-free photocatalyst for water splitting.
将碳纳米点（C点）与石墨相氮化碳（g-C3N4）相结合可形成一种无金属体系，该体系最近已证明在光催化水分解制氢方面具有显著增强的性能[《科学》，2015年，第347卷，第970 - 974页]。然而，其潜在的光催化机制尚未完全确立。在此，我们进行了密度泛函理论（DFT）计算，以研究g-C3N4与三角形/六边形C点之间的相互作用。我们发现，混合的C点/g-C3N4可形成II型范德华异质结，从而导致带隙显著减小。C点修饰的g-C3N4增强了光生电子和空穴对的分离以及复合材料的可见光响应。有趣的是，通过杂化泛函方法计算得到的C点和g-C3N4的能带排列表明，在混合的C点/g-C3N4用于水分解时，C点充当光谱敏化剂。我们的结果为这种用于水分解的无金属光催化剂提供了新的理论见解。
